ABSTRACT
ABSTRACT: There is a the perception among some that asphalt pavements, particularly as surfaces for parking lots for facilities such as shopping centers, apartment buildings, and office buildings, are contributing to global warming through the so called urban heat island effect. The contention is that Portland Cement Concrete (PCC) is a less significant contributor to global warming via this mechanism and is, therefore, the preferred paving material. This rationale with some supporting science has succeeded sufficiently to result in PCC being given an advantage in building codes toward obtaining building LEED certification. The basis for this thought is that, since asphalt pavements are black and concrete pavements are white, the asphalt will absorb more solar radiation and become hotter during the course of daylight hours. Because empirical data in urban environments is difficult to obtain and clouded by a myriad of other effects Computational Fluid Dynamics (CFD) was chosen to compare an idealized configuration of an office building and parking lot. Only the reflectivity (albedo) of the parking lot was altered to simulate both asphalt and concrete. The results showed that the building surface temperature was actually higher for the concrete parking lot than the asphalt lot indicating a higher cooling load would be required. These results run counter to commonly held beliefs about the superiority of concrete pavements in urban environments and suggest the need to re-examine the suitability of asphalt pavement in urban settings.
